In depositing implants, such as the radio-active gold implants for the treatment of cancer, and the like, it is important that the implants be deposited in spaced intervals and that the user of the implant mechanism be constantly advised of the number of implants deposited as the process progresses. It is an object of this invention to provide an accurately calibrated implant injector that will provide a measured movement of the plunger which moves the implant into the tissue and assures the deposit of a single implant with each rotation of the outer member.